1. Field of the Invention
The present invention relates to an apparatus for the slicing of meat and, more particularly, to an apparatus for effecting a spiral slice cut in a ham, beef roast, or the like.
2. General Background
There exists a number of different apparatus for spiral slicing of meats, such as hams or roasts, about the bone located in the cut of meat. These devices have a number of common features. First, they typically include a rotating chuck assembly. The chuck assembly is driven by some motorized means and is designed to hold the meat to be cut, thereby rotating the meat about the chuck assembly rotational axis. Second, the device includes a rotating circular saw blade, disposed in a plane generally perpendicular to the rotational axis of the chuck assembly and including a means for driving the saw blade, for cutting the meat. To facilitate the mechanics of the cutting process, provisions are generally made for adjusting the position of the saw blade relative to the stated plane. Third, the device includes a means of gradually linearly indexing the saw blade assembly relative to the meat. The index axis is typically parallel to the chuck assembly rotational axis. Lastly, the saw blade assembly typically includes a means for rotating the saw blade about the index axis, thereby laterally positioning the saw blade and bringing the blade into cutting engagement with the meat. The rotation of the meat, when in contact with the saw blade, and the linear indexing of the blade relative to the meat, effect a generally continuous spiral cut of the meat about the bone. While the concept of the apparatus has been accepted, there persists a number of problems associated with existing devices, which will be described hereinafter.
One such device was set forth in U.S. Pat. No. 4,441,411, issued to Mullins. In this device, the saw blade assembly was vertically indexed relative to the meat by linking the saw blade assembly to a first hydraulic vertical drive cylinder. However, there were a number of problems with this type of hydraulic vertical indexing system.
First, prolonged use of the device increased the temperature of the hydraulic fluid and thereby caused a change in fluid viscosity. This change in fluid viscosity resulted in an undesired variation in the vertical indexing rate, which varied the cut from the desired thickness of the meat slices. Further, it is normal for conventional hydraulic systems to operate in the pressure range of 1000-2000 psi, where the Mullins device operated in the range of 50-60 psi. Prolonged use of the device resulted in wear in the seals and other elements of the hydraulic circuit, which combined with operating out of normal hydraulic circuit pressure range and other operational aspects described in greater detail below, caused variations up to .+-.10 psi. during the course of operation. These pressure variations also resulted in a non-uniform meat slice thickness.
Second, consistency in vertical positioning is important in a meat slicing operation. In the interest of safety, the slicing of meat is a man-attended operation. Commercial operations often call for the operator to be called away from the slicing operation for other tasks. Safety procedures call for the blade to be disengaged from the meat and the apparatus de-energized when the operator is away. Due to variations in fluid temperature and wear in hydraulic system components, the Mullins device often experienced a "bleed down" or leakage within the hydraulic system. The bleed down resulted in a variation in the height of the saw blade from the height at the time of interruption of operations. It was difficult for the operator to vertically re-index the saw blade to the position where disengagement occurred when resuming operations, which yielded a non-uniform cut.
A hydraulic cylinder linkage was also used in U.S. Pat. No. 4,441,411 to laterally position the saw blade into engagement with the meat. Herein, a second, horizontally disposed, hydraulic cylinder, operating in the same hydraulic system, was linked to the shaft linkage of the vertical indexing cylinder through an offset arm. Actuation of the second hydraulic cylinder caused the shaft linkage of the vertical indexing cylinder to rotate about the vertical indexing axis and laterally positioned the saw blade relative to the meat to be cut.
The problem with this arrangement is a peculiarity of the type of meat to be cut. The cuts of meat typically have a first bone, which is generally aligned with the rotational axis of the chuck assembly. Many of the cuts, such as picnic hams and the like, also have a second or "aitch" bone, which are offset and eccentrically positioned relative to the first bone. In order to properly effect a spiral cut, it is necessary for the saw blade to cut circumferentially about the first bone. However, the saw blade will come into contact with the eccentrically positioned aitch bone during the rotation of the meat, causing a destructive wearing of the saw blade and possible chipping of the aitch bone, thereby ruining the cut of meat.
This problem is generally addressed through the inclusion of an override handle attached to the saw blade assembly to permit the operator to withdraw the saw blade a sufficient distance to "ride" about the aitch bone. Because the aitch bone is not visible during the cutting operation, this technique requires the operator to acquire a "feel" for when the blade is in contact with the aitch bone, so as to manually override the engagement force of the second hydraulic cylinder. By feeling the resistance met by the saw blade, the operator is able to keep the saw blade in light contact with the bones in the meat as it rotates about the chuck assembly axis.
The problems with the hydraulic positioning system of U.S. Pat. No. 4,441,411 arose from the relative incompressibility of hydraulic fluid. First, it was difficult for the operator to determine when the saw blade is coming in contact with either the first or second bone. Where the operator was unable to feel the contact through the override handle, meat spoilage and blade breakdown could occur. Second, the amount of force required to overcome the engagement force supplied by the second hydraulic cylinder was excessive due to the relative incompressibility of the hydraulic fluid. A biasing spring within the second hydraulic was provided for in this device to help overcome fluid incompressibility; however, it too operated against fluid pressure. Third, by being coupled to the same hydraulic circuit as the vertical indexing cylinder, overriding the lateral positioning force varied the hydraulic system pressure, causing a variation in vertical index rate and a non-uniform slice thickness. During the course of daily operations, an establishment utilizing this type of apparatus may cut an average of 10-15 hams per day, with peak days having as many as 60. Over an average day's operation, an operator may have been required to exert from 68 to 71 pounds of force over a distance of 4-6 inches to withdraw the blade a sufficient distance over the aitch bone. Further, the operator performed this manual override an average of 12-15 times per ham. Thus, during the course of an average day, the operator expended over 5000 ft-lbs during slicing operations. On peak days, this expenditure was as high as 25,200 ft-lbs. It will be appreciated that the amount of override work expended over a day's operation was highly fatiguing to the operator and could result in spoilage of meat due to miscuts.
Other embodiments of this type of apparatus varied the means by which each of the basic functions were carried out. U.S. Pat. No. 4,287,820 disclosed a clutch actuated, chain driven, carriage for vertically indexing the saw blade assembly. U.S. Pat. No. 4,332,190 utilized a gear-driven, threaded shaft to vertically index the saw blade assembly. One disadvantage common to both of the above devices was that the rate of vertical indexing was dependent upon the rotation rate of the chuck assembly. In U.S. Pat. No. 4,287,820, the relationship was determined by the gear which drove the vertical indexing carriage. In U.S. Pat. No. 4,332,190, the relationship was determined by a gear ratio and lead screw. Both of these devices could vary this relationship only upon changing either a lead screw or gear. This presented a significant disadvantage in commercial operations where slice thickness varied with customer demand.
A similar problem exists in U.S. Pat. No. 2,599,328 wherein the cutting rate was controlled by the rate of rotation. In this apparatus, the meat was rotated and simultaneously vertically indexed. Instead of using a circular saw blade, a reciprocating saw was used to cut the meat. The reciprocating saw was gear driven from the same motor which controlled the vertical indexing and rotation. The problem with this device was that the vertical indexing, meat rotation and saw speed were all interrelated. Slice thickness was varied by changing the vertical index lead screw; a time consuming operation.
Accordingly, a meat slicing apparatus is desired which does not suffer from the disadvantages of hydraulic systems and which provides a higher degree of selection of cutting thickness than that provided by strictly mechanical systems. The present invention is designed to overcome the above problems and also provides a method for spiral cutting boneless meats.